An increased need for information exchange at high speeds and in large quantities has led to the development of optical communication technology, by which transmission speeds have passed beyond the level of gigabits per second to terabits per second. With such developments in optical communication technology, it is now possible to establish an optical communication environment within the home, to utilize optical communication in everyday activities.
Low-cost optical transceivers are being manufactured, to meet the demands for optically communicating transceivers at home and in the office. An optical transceiver module is composed of an optical subassembly, electronic circuits for generating and processing electric signals, and the like, and generally has standardized dimensions for its size and input/output terminals.
Thus, in an optical transceiver, the optical subassembly plays the most crucial role and ultimately determines the cost of the optical transceiver. As the optical subassembly performs alignment with the optical fibers, it requires extremely high precision in its structure. In the related art, the light-emitting and light-receiving elements were optically coupled and secured by a method of active alignment, which utilizes a high-precision stage and an external power source. Such an active alignment method involves finding the position of maximum optical coupling by precisely adjusting the optical fibers not only along the X-Y-Z axes but also about the rotational axis, while keeping the light-emitting or light-receiving elements operational, and sensing in real time the degree of alignment with respect to the optical fibers. This can be costly in terms of working hours, process equipment, process costs, etc. In contrast, a passive alignment assembly of a pick-and-place method does not require separate equipment for operating a light-emitting or light-receiving element, and simply uses predefined position information to assemble parts by using a robot or by looking through a microscope, and as such requires less process time, equipment, costs, etc.
Such a passive optical alignment method entails the problem that it is very difficult to fabricate an optical subassembly in the form of a receptacle with which to freely attach and detach optical fibers. Thus, there is a need for a new structure for an optical subassembly having the form of a receptacle and for a new method of passive optical alignment.